The present research proposal is directed toward the chemical synthesis of glycosides of biological importance. A number of different protecting groups such as allyl, benzyl, chloroacetyl, silyl and other protecting groups for hydroxyl group will be utilized in our investigations. Different glycosylating reagents such as oxazolines, 1,2-0-alkyl orthoesters, 1,2 thio orthoesters, and various other glycosyl halides containing persistent and temporary protecting groups will be efficiently prepared and further employed in the sequential synthesis of complex saccharides. use of trimethylsilyl bromide, and trimethylsilyliodide will be extensively made for the preparation of various glycosyl-1-halides. Halide ion catalyzed reaction will be applied for the preparation of desired 1,2 cis linked glycosides. The scope of catalysts such as silver triflate, silver salicylate and other catalysts with certain sugar halides will be examined in the proposed studies. Generally, the aglycons having persistent protecting groups on other hydroxy groups will be employed as starting material for the synthesis of higher saccharides. In the proposed program, a limited number of modified saccharides will be also synthesized. In our investigations, attempts will be made on the isolation of pure material after each step of a chemical reaction if possible. Preparative t.l.c. technique will further establish the homogeneity of di and trisaccharide derivatives and if possible including tetrasaccharide. The synthetic compounds will be also characterized by their n.m.r. and infra red studies. Synthetic sugar derivatives will be useful for studies related to glycosidases, glycosyltransferases, lectins and antigens.